A hybrid vehicle may include an engine and a motor to propel the vehicle. The engine and motor may be activated at different times or at a same time. The engine may be used during long cruise conditions while the motor may be used to launch the vehicle from a stop. The engine and motor may both be activated during conditions where engine efficiency may be increased via operating the motor to meet a requested driver demand torque. However, not all combinations of engine torque and motor torque to provide the desired driver demand torque are equal in powertrain efficiency. Therefore, it may be desirable to provide a way of selecting engine and motor torques that increases powertrain efficiency.
The inventors herein have recognized the above-mentioned issues and have developed a powertrain operating method, comprising: distributing a driver demand torque request between an engine and a motor responsive to a first battery charging curve and a first battery discharging curve while not operating a vehicle in cruise control mode; and distributing the driver demand torque request between the engine and the motor responsive to a second battery charging curve and a second battery discharging curve while operating the vehicle in cruise control mode.
By distributing a driver demand torque request between a motor and an engine based on whether or not a vehicle in which the motor and engine operate is in a cruise control mode, it may be possible to provide the technical result of increased powertrain or driveline efficiency while the vehicle is operating in cruise control mode. For example, battery charging and discharging curves may be established for operating a vehicle in cruise control mode and for not operating the vehicle in cruise control mode. The battery charging and discharging curves for operating the vehicle in cruise control mode may direct engine operating conditions closer to a center of an area of low fuel consumption region of an engine brake specific fuel consumption map so that engine efficiency and motor efficiency may be improved as compared to if the engine and motor were operated based on the battery charging and discharging curves for not operating the vehicle in cruise control mode.
The present description may provide several advantages. For example, the approach may provide increased powertrain efficiency. Further, the approach may increase the possibility of operating the vehicle's motor so as to improve engine operating efficiency. Additionally, the approach may reduce transmission shifting by augmenting engine torque with motor torque so that vehicle speed may be maintained without downshifting.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.